Utilization of optical wood chip analyzer in pulping and chipping process, 2006 Engineering, Pulping, and Environmental Conference

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Wood chip analyses have traditionally utilized the TAPPI and SCAN mechanical test methods. Although hand-sorting chips is the most accurate method of measuring chip size distribution, it is labor-intensive and time-consuming. Consequently, the test results are not used in online process control.

Mechanical devices that simulate hand-sorting chips are typically used to improve productivity and practicality. However, these devices introduce result variability and are expensive to maintain due to component wear life and calibration problems.

Measuring devices based on machine vision can be used to measure all three dimensions of the wood chip simultaneously. The result is width, length and thickness distributions from a test sample of wood chips that can present results in various forms. The results can be sorted to emulate a TAPPI or SCAN report or they can be configured to provide customized reports to assist in studying specific issues. A chip quality analyzer can be equipped with an automated sampler to provide continuous analysis of chip flow to assist in monitoring the chipping process and purchased chip supply, or controlling digester parameters.

Further, when the device is equipped with a special conveyor, several separate samples can be loaded on to the conveyor for automated analysis. This is a useful way to measure samples from various locations or to analyze the quality of purchased chips.

Modern optical chip analyzers provide extremely accurate measurement of all the chips in the sample, quickly, with very low maintenance, and very little manpower. This paper presents an overview of an optical chip quality analyzer and three examples utilizing this technology.